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Burkholderia pseudomallei (Bp) is the causative agent of melioidosis, an opportunistic but serious human disease endemic to Southeast Asia and Northern Australia. The ‘Bp-group’ includes Bp and the closely-related organisms B. thailandensis (Bt) and B. oklahomensis (Bo), all of which are usually soil-dwelling saprophytes, and B. mallei (Bm) which is an equine-host-adapted pathogen. Bt is virulent in a number of invertebrate models but is generally non-pathogenic for mammals and is often used as a surrogate for the study of virulence mechanisms shared with Bp. Experiments to assess the potential of the Tobacco Hawkmoth Manduca sexta as a model host for Bp or Bt infection revealed surprising results. Bp, Bt and Bo were all lethal to M. sexta larvae. This is the first report of Bo virulence in an infection model. Additionally, the relative virulence of the three species was the reverse of that reported in humans and in larvae of the Greater Waxworm Galleria mellonella. Despite that, well-known hallmarks of Bp-group pathogenesis in mammalian hosts – intracellular survival and multiplication, actin remodelling and acute sepsis – were observed in M. sexta infection during a fluorescent confocal microscopy time-course study. M. sexta feeding experiments with Bt and Bo indicated that cultures of these bacteria are also pathogenic via the oral route, which is likely to be relevant for natural insect-bacteria interactions. Cell-free supernatant of Bo was as harmful to larvae as complete culture, supporting previous suggestions that Bp-group bacteria produce toxins or paralytic agents that are active against invertebrates. Finally, Rapid Virulence Annotation (RVA) was performed as a genome-wide screen for virulence determinants of Bp strain K96423, using three invertebrate bioassays with a recombinant expression library. In response to problems with the reproducibility of biologically active clones, a new statistical approach was devised which enabled quantitative identification of the most convincing RVA hits.

A Baía do Almirantado (Ilha Rei George, Antártica) possui diversas pequenas enseadas de águas rasas, que sustentam uma abundante fauna bentônica. O regime de marés e de ventos é responsável pelo hidrodinamismo na baía e pela interação com as águas do Estreito de Bransfield. Portanto, trata-se de uma área que pode apresentar uma elevada abundância de larvas de invertebrados marinhos. A distribuição espaço-temporal de larvas pelágicas em águas rasas costeiras da Baía do Almirantado foi estudada entre outubro de 2002 e maio de 2003, e outubro de 2003 e agosto de 2004 em 12 estações rasas (0 a 15 m, ou até 30 m). Também foram amostradas, sazonalmente, quatro estações de maior profundidade, entre 0 a 30 m e 30 a 130 m da coluna de água, entre outubro de 2003 e abril de 2004. Amostras de plâncton foram coletadas com rede cônica de plâncton com malha de 150 µm nas três enseadas da baía (Martel, Mackellar e Ezcurra) e na entrada do seu canal principal. Larvas de diferentes grupos ocorreram em todo o período de estudo. No primeiro ano, a abundância total foi maior que no segundo e, em especial, no verão. As larvas véliger de Gastropoda foram mais abundantes, representando 84% do total do meroplâncton, no primeiro ano de amostragem. No ano seguinte, larvas trocófora foram predominantes (31% do total), seguidas de Gastropoda e Nemertea. Os resultados mostraram uma evidente variação interanual da densidade e da composição do meroplâncton, mas sem um padrão nítido de sazonalidade para determinados grupos. O congelamento da baía no inverno do primeiro ano de amostragem (2002) pode ter afetado a reprodução dos invertebrados bentônicos e a produção de larvas. Quanto à distribuição batimétrica, a abundância média do meroplâncton total foi maior na camada profunda do que na de superfície, na primavera-verão, mas espacialmente a densidade foi semelhante entre as áreas nas distintas camadas. A variabilidade na abundância e composição larval pode estar relacionada à hidrografia e a padrões reprodutivos das espécies bentônicas com desenvolvimento indireto, cujos ciclos reprodutivos são afetados por características ambientais. Em termos gerais, o meroplâncton coletado na Baía do Almirantado foi qualitativamente similar (quanto aos grupos de larvas) ao descrito para outras partes da Antártica. / Admiralty Bay (King George Island, Antarctica) has many small inlets of shallow waters, which supports an abundant benthic fauna. Tidal and wind regime are responsible for the hydrodynamics in the bay and for the interaction with the waters of the Bransfield Strait. Therefore, it is an area that can present a high abundance of marine invertebrate larvae. Spatio-temporal distribution of pelagic larvae in shallow coastal waters of Admiralty Bay was studied between October of 2002 and May of 2003, and October of 2003 and August of 2004 in twelve shallow stations (0 to 15 m, or up to 30 m). Four deeper stations were also seasonally sampled (0 to 30 m and 30 to 130 m of water column) between October of 2003 and April of 2004. Plankton samples were collected with a conical net, with mesh size of 150 µm, in the three inlets of the bay (Martel, Mackellar and Ezcurra) and in the entrance of its main channel. Larvae of different groups occurred in the whole studied period. In the first year, the total abundance was higher than in the second and, especially, in the summer. The veliger larvae of Gastropoda were more abundant, representing 84% of the total meroplankton in the first year of sampling. In the following year, trochophore larvae were predominant (31% of the total), followed by Gastropoda and Nemertea. The results showed an evident interannual composition and density variation of meroplankton, but without a clear pattern of seasonality for certain groups. The freezing of the bay in the winter of the first year could have influenced the benthic invertebrate\'s reproduction and larvae production. Regarding to the bathymetric distribution, the mean abundance of the total meroplankton was higher in the deeper layer than in the surface in spring-summer, however, spatially the density was similar among the areas in the different layers. The variability in the larval composition and abundance may be related to the local hydrography and specific reproductive pattern of the benthic species with indirect development, whose reproductive cycles are affected by environmental characteristics. In general terms, the meroplankton collected in Admiralty Bay was qualitatively similar (in view of the larval groups) to the described for other parts of Antarctica.

Submitted by Maicon Juliano Schmidt (maicons) on 2015-07-03T17:37:20Z No. of bitstreams: 1 Hugo Schmidt Neto.pdf: 3763887 bytes, checksum: 8a837a24fd2ae953f70fb46e18ca9e16 (MD5) / Made available in DSpace on 2015-07-03T17:37:20Z (GMT). No. of bitstreams: 1 Hugo Schmidt Neto.pdf: 3763887 bytes, checksum: 8a837a24fd2ae953f70fb46e18ca9e16 (MD5) Previous issue date: 2013-01-31 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPQ – Conselho Nacional de Desenvolvimento Científico e Tecnológico / No município de Taió, Santa Catarina, o Membro Paraguaçu apresenta uma expressiva fauna de invertebrados marinhos contidos em camadas de areias muito finas, denominadas informalmente de Camadas Taió. Sua assembleia se desenvolveu em um período pós-glacial e foi influenciada pelas condições do degelo do final do Grupo Itararé. Assim o presente trabalho teve como objetivo realizar a análise paleoecológica destes depósitos a fim de elucidar o impacto do aporte de águas de degelo no mar Taió. Para tanto foi realizado um estudo tafonômico dos repositórios das instituições científicas do Rio Grande do Sul, Santa Catarina e São Paulo, tal como dos registros fósseis nos afloramentos (in loco). Os perfis das sucessões sedimentares, das áreas fossilíferas foram correlacionados a partir da comparação de suas fácies. As assinaturas tafonômicas mostram sinais de pouco transporte e rápido soterramento, com pouca colonização dos bioclastos por organismos espongiários. O padrão de ocorrência da biofábrica Rosselia isp. indica a ação de eventos de tempestade e alta frequência sedimentar. Uma maior quantidade de restos vegetais na base da sucessão indica uma maior proximidade da costa, enquanto formas diminutas de moluscos e equinodermos, ocorrentes nas fácies que sugerem uma zona de shoreface, indicam águas de baixas temperaturas. Os dados alcançados neste trabalho indicam que as águas do degelo do final do Carbonífero continuaram impactando a fauna marinha do Mar Paraguaçu pela flutuação de sua salinidade e de seu condicionamento a baixas temperaturas. / At the Taio city, Santa Catarina State, the Paraguassu Member presents a significant marine invertebrate fauna contained in layers of very fine sand, informally designed Layers Taio. Its congregation has developed into a post-glacial conditions was influenced by the melting of the final Itararé Group. Thus, the present study aimed to conduct paleoecological analysis of these deposits in order to elucidate the impact of the inflow of water from melting sea Taio. Therefore, went make a taphonomic study of repositories of scientific institutions of Rio Grande do Sul, Santa Catarina and São Paulo states, as the fossil record in outcrops (in situ). The profiles of sedimentary successions, fossiliferous areas were correlated from the comparison of their facies. The taphonomic signatures show little signs of rapid transportation and burial, with little colonization by organisms of bioclasts sponges. The pattern of occurrence of biofabric Rosselia isp. indicates the action of storm events and high-frequency sediment. A larger quantity of plant debris on the basis of the sequence indicates closer proximity to the coast, while forms tiny molluscs and echinoderms, suggesting facies that occur in a zone of shoreface indicate low water temperatures. The data obtained in this work indicate that the waters of the melting of the end of the Carboniferous continued impacting the marine fauna of the Sea Paraguaçu by floating its salinity and his conditioning at low temperatures.

Submitted by Fabricia Fialho Reginato (fabriciar) on 2015-08-28T00:06:02Z No. of bitstreams: 1 RegianeWusth.pdf: 725429 bytes, checksum: e20257e94144c76e5a69704462ec15a8 (MD5) / Made available in DSpace on 2015-08-28T00:06:02Z (GMT). No. of bitstreams: 1 RegianeWusth.pdf: 725429 bytes, checksum: e20257e94144c76e5a69704462ec15a8 (MD5) Previous issue date: 2014 / Nenhuma / As áreas úmidas estão entre os ecossistemas que mais contribuem para a diversidade biológica. Por outro lado, também são considerados os ecossistemas mais ameaçados pela ação humana. As áreas úmidas intermitentes são definidas pelo seu hidroperíodo, caracterizado pelo número de meses em que esses ecossistemas apresentam água superficial durante um ano. O hidroperíodo é um fator importante que influencia as comunidades de invertebrados em áreas úmidas, afetando diretamente as espécies que necessitam completar parte ou todo o seu ciclo de vida na água. Em áreas úmidas intermitentes, espécies de invertebrados aquáticos produzem propágulos dormentes capazes de resistir à dessecação, constituindo uma reserva ecológica e evolutiva fundamental em resposta às condições adversas relacionadas às flutuações no regime hidrológico e de outros fatores ambientais. O objetivo geral desse estudo foi analisar a emergência de invertebrados aquáticos via bancos de propágulos dormentes em sedimentos secos de áreas úmidas intermitentes de altitude no Sul do Brasil, relacionando as respostas da comunidade com diferentes hidroperíodos. Os objetivos específicos foram: 1) Comparar a riqueza, a abundância e a composição de invertebrados aquáticos emergentes de propágulos dormentes entre áreas úmidas que apresentam diferentes hidroperíodos, e 2) Identificar táxons de invertebrados aquáticos emergentes de propágulos dormentes que possam ser utilizados como indicadores de diferentes hidroperíodos de áreas úmidas de altitude no Sul do Brasil. Foram realizadas coletas de sedimento seco em nove áreas úmidas distribuídas em três tratamentos de hidroperíodo (curto, médio e longo) localizadas nos Campos de Cima da Serra do Sul do Brasil, dentro do bioma Mata Atlântica. Em laboratório, o sedimento seco foi hidratado com água destilada e mantido sob temperatura e fotoperíodo controlados. Os invertebrados foram amostrados no dia posterior à hidratação, e semanalmente durante 10 semanas. Um total de 19.868 indivíduos distribuídos em 11 táxons foi encontrado ao longo do experimento. A riqueza, a abundância e a composição de invertebrados aquáticos não variaram entre os diferentes hidroperíodos. Entretanto, Karualona muelleri foi mais abundante nas áreas úmidas com hidroperíodos curto e médio e Kurzia polyspina foi mais abundante nas áreas úmidas com hidroperíodo longo. Os tardígrados foram abundantes em áreas com hidroperíodo médio. Nosso estudo demonstrou que as áreas úmidas de altitude estudadas podem ser facilmente recolonizadas após um período de seca e que as comunidades dormentes de invertebrados aquáticos são fundamentais no processo de sucessão ecológica nesses importantes ecossistemas do Sul do Brasil. / The wetlands are among the ecosystems that contribute the most to biological diversity. On the other hand, are also considered the most threatened ecosystems by human action. The intermittent wetlands are defined by its hydroperiod, characterized by the number of months in which those present surface water during a year. The hydroperiod is an important factor to invertebrate communities in wetland systems, directly affecting the species that need to complete part or all of their life cycle in the water. In intermittent wetlands, species of aquatic invertebrates produce dormant propagules able to resist desiccation, constituting a fundamental evolutionary and ecological reserve in response to adverse conditions related to fluctuations in the hydrological regime and other environmental factors. The main objective of this study was to analyze the emergence of aquatic invertebrates via banks of dormant propagules in dry sediment of intermittent wetlands located in high altitudes in southern Brazil, relating the responses of the community with different hydroperiods. The specific objectives are: 1) Compare the richness, abundance and composition of drought-resistant aquatic invertebrates between wetlands that have different hydroperiods, and 2) Identify taxa of drought-resistant aquatic invertebrates which may be used as indicators of different hydroperiods in wetlands in southern Brazil. Sediment samplings were carried out in nine intermittent wetlands distributed in three treatments of hydroperiod (short, medium and long) located in southern Brazil, within the Atlantic forest biome. In the laboratory, the dry sediment was hydrated with distilled water and kept under controlled temperature and photoperiod. The invertebrates were sampled on the first day after hydration, and weekly for 10 weeks. A total of 19,868 individuals distributed in 11 taxa were found throughout the experiment. The richness, abundance and composition of aquatic invertebrates did not vary between the different hydroperiods. However, Karualona muelleri was more abundant in wetlands with short and medium hydroperiods and Kurzia polyspina, on the other hand, was most abundant in wetlands with long hydroperiod. The tardigrades were abundant in wetlands with medium hydroperiod. Our study showed that the studied wetlands can be easily recolonized after a dry period and that the drought-resistant aquatic invertebrate communities play a critical role in the ecological succession in southern Brazil wetlands.

Medusozoan jellyfish (Classes Scyphozoa and Hydrozoa) have gained a degree of worldwide notoriety in the last fifteen years, particularly as anthropogenic influences such as climate change and overfishing push some ecosystems toward their advantage (Lynam et al. 2005, Purcell and Arai 2001, Purcell et al. 2007, Purcell 2012, Flynn et al. 2012, Dawson et al. 2014). Accordingly, both the lay and scientific media have paid a good deal of attention to jellyfish bloom phenomena and their impacts on human activities, but the bulk of this attention has been devoted to larger, visually obvious species of Class Scyphozoa. Only recently have their smaller cousins, the hydrozoans, come to be recognized as potentially problematic. This thesis examines population ecology of hydrozoan medusae (hydromedusae) and their implications for salmon aquaculture in Scotland. My review of available literature has found hydrozoans to be a recognized - though under- studied - problem for Scottish salmon (Chapter 1, Prospective monitoring of hydromedusa populations at salmon aquaculture facilities). Typically, hydrozoan populations at salmon farms have been discussed in the scientific literature only in the context of extremely dense visible blooms or in the wake of major mortality incidents. This retrospective, rather than prospective, approach has left a dearth of knowledge pertaining to hydromedusan interactions with farmed fish, with both fish welfare and industry economics vulnerable to future blooms. This thesis sought to build a basis for the goals of prediction, avoidance, and mitigation of harmful hydrozoan jellyfish blooms. First and foremost, this required the development of a prospective time-series dataset of hydromedusan occurrences at salmon farms (Chapter 2, Bacterial genera biodiversity in three medusozoan species in Shetland). To this end, four farms were recruited as participants across a three-year survey. Weekly plankton tow-based sampling at these sites identified which hydrozoan species could be expected to produce blooms, the seasonality of such blooms, and the pathological sequelae that could be expected in salmon after exposure to such blooms. Following one particularly dramatic bloom, a spike in gill pathologies in salmon was observed, followed by a spike in overall mortality and the eventual loss of up to £2.5 million value as the fish were humanely culled. This survey also demonstrated that hydromedusan blooms are usually spatially and temporally patchy, limiting the opportunities for geographically-encompassing predictive power. Instead, individual aquaculture facilities may require site-specific risk assessment and planning frameworks to monitor and cope with blooms. Potential methods for continued basic monitoring and a mitigation strategy based on minimizing contact between fish and high-density blooms are suggested. A second mitigation goal examined the theory that medusae may act as vectors for microbial pathogens, particularly Tenacibaculum maritimum (Ferguson et al. 2010, Delannoy et al. 2011; Chapter 3). Sampling methods designed to target T. maritimum were employed with the aim of determining its distribution and role as a symbiont in various life stages of medusozoan species. While T. maritimum itself was not observed, a number of other fish pathogens were found in close association with several species. This included Aeromonas salmonicida, known to cause furunculosis in aquaculture of both salmon and trout (Nomura et al. 1992). Further work is required to piece together the nature of these associations. Finally, Chapter 2 identified a particular hydrozoan genus, Obelia, as a likely significant contributor to blooms at salmon aquaculture sites. One of its species, O. geniculata, has a widely distributed and well-recognized benthic colonial life stage (called the hydroid stage) in Scottish nearshore sublittoral environments. In attempting to sample these hydroids from previously well-colonized sites in Shetland in late 2012, it became apparent that a severe local reduction in the benthic population was taking place. This allowed for the opportunity to study phylogeographic population structure - i.e. the boundaries of its gene pool(s) in Scottish waters and its potential for dispersal during one seasonal reproductive period - using a molecular study of the mitochondrial cytochrome oxidase subunit I (mtCOI) gene (Chapter 4, Phylogeographic analysis of Obelia geniculata populations in the north of Scotland). In sampling immediately after the observed dieback, O. geniculata was found to follow a south-to-north pattern of genetic grouping, as well as a confirmed dieback. However, this pattern disappeared in samples collected after the population had recovered, probably due to the immigration of genetically novel individuals. This finding, in conjunction with the spatial-temporal patchiness found in the medusa bloom stage, suggests the importance of the larval stage as the primary stage for dispersal in the plankton. This study was also able to compare present population genetic data with a set of O. geniculata mtCOI data collected between 1998 and 2002. The combined data potentially show a high degree of mixing across a number of North Atlantic regions, including Icelandic and North American sites. Further investigation will be required to discern whether this pattern is temporally based (i.e. artefact of 15 years' elapsed time in opportunities for population mixing), or whether ecological, anthropogenic, or combined mechanisms are facilitating rapid transport of propagules to yield a well-mixed population. Further work in refining prediction and mitigation is still needed, as are effective veterinary interventions in the event of blooms. Continued study into the ecological patterns of colonization and dispersal may help to minimize exposure to blooms, by helping to assess site-based risks. This research forms the basis for such studies into hydrozoan interactions with salmon farms in Scotland, and how the industry might seek to minimize their impacts.

A Baía do Almirantado (Ilha Rei George, Antártica) possui diversas pequenas enseadas de águas rasas, que sustentam uma abundante fauna bentônica. O regime de marés e de ventos é responsável pelo hidrodinamismo na baía e pela interação com as águas do Estreito de Bransfield. Portanto, trata-se de uma área que pode apresentar uma elevada abundância de larvas de invertebrados marinhos. A distribuição espaço-temporal de larvas pelágicas em águas rasas costeiras da Baía do Almirantado foi estudada entre outubro de 2002 e maio de 2003, e outubro de 2003 e agosto de 2004 em 12 estações rasas (0 a 15 m, ou até 30 m). Também foram amostradas, sazonalmente, quatro estações de maior profundidade, entre 0 a 30 m e 30 a 130 m da coluna de água, entre outubro de 2003 e abril de 2004. Amostras de plâncton foram coletadas com rede cônica de plâncton com malha de 150 µm nas três enseadas da baía (Martel, Mackellar e Ezcurra) e na entrada do seu canal principal. Larvas de diferentes grupos ocorreram em todo o período de estudo. No primeiro ano, a abundância total foi maior que no segundo e, em especial, no verão. As larvas véliger de Gastropoda foram mais abundantes, representando 84% do total do meroplâncton, no primeiro ano de amostragem. No ano seguinte, larvas trocófora foram predominantes (31% do total), seguidas de Gastropoda e Nemertea. Os resultados mostraram uma evidente variação interanual da densidade e da composição do meroplâncton, mas sem um padrão nítido de sazonalidade para determinados grupos. O congelamento da baía no inverno do primeiro ano de amostragem (2002) pode ter afetado a reprodução dos invertebrados bentônicos e a produção de larvas. Quanto à distribuição batimétrica, a abundância média do meroplâncton total foi maior na camada profunda do que na de superfície, na primavera-verão, mas espacialmente a densidade foi semelhante entre as áreas nas distintas camadas. A variabilidade na abundância e composição larval pode estar relacionada à hidrografia e a padrões reprodutivos das espécies bentônicas com desenvolvimento indireto, cujos ciclos reprodutivos são afetados por características ambientais. Em termos gerais, o meroplâncton coletado na Baía do Almirantado foi qualitativamente similar (quanto aos grupos de larvas) ao descrito para outras partes da Antártica. / Admiralty Bay (King George Island, Antarctica) has many small inlets of shallow waters, which supports an abundant benthic fauna. Tidal and wind regime are responsible for the hydrodynamics in the bay and for the interaction with the waters of the Bransfield Strait. Therefore, it is an area that can present a high abundance of marine invertebrate larvae. Spatio-temporal distribution of pelagic larvae in shallow coastal waters of Admiralty Bay was studied between October of 2002 and May of 2003, and October of 2003 and August of 2004 in twelve shallow stations (0 to 15 m, or up to 30 m). Four deeper stations were also seasonally sampled (0 to 30 m and 30 to 130 m of water column) between October of 2003 and April of 2004. Plankton samples were collected with a conical net, with mesh size of 150 µm, in the three inlets of the bay (Martel, Mackellar and Ezcurra) and in the entrance of its main channel. Larvae of different groups occurred in the whole studied period. In the first year, the total abundance was higher than in the second and, especially, in the summer. The veliger larvae of Gastropoda were more abundant, representing 84% of the total meroplankton in the first year of sampling. In the following year, trochophore larvae were predominant (31% of the total), followed by Gastropoda and Nemertea. The results showed an evident interannual composition and density variation of meroplankton, but without a clear pattern of seasonality for certain groups. The freezing of the bay in the winter of the first year could have influenced the benthic invertebrate\'s reproduction and larvae production. Regarding to the bathymetric distribution, the mean abundance of the total meroplankton was higher in the deeper layer than in the surface in spring-summer, however, spatially the density was similar among the areas in the different layers. The variability in the larval composition and abundance may be related to the local hydrography and specific reproductive pattern of the benthic species with indirect development, whose reproductive cycles are affected by environmental characteristics. In general terms, the meroplankton collected in Admiralty Bay was qualitatively similar (in view of the larval groups) to the described for other parts of Antarctica.

Beavers were virtually extirpated from North America during the fur trade, but populations have since recovered. Dams built by recolonizing beaver alter stream habitat by forming deep, slow ponds within the streams. Such changes to the habitat is likely to have consequences for organisms such as macroinvertebrates and fish. The objective of this study was to identify the differences in the macroinvertebrate and trout community in beaver ponds and lotic (e.g. flowing reaches of a stream) reaches in tributaries to the Logan River in northeastern Utah. The macroinvertebrate community of beaver ponds had fewer species, fewer numbers, and lower biomass of macroinvertebrates compared to lotic reaches. Macroinvertebrates that consume leaf litter and predators that prey on other macroinvertebrates characterized beaver pond macroinvertebrate communities. In contrast, lotic reaches contained macroinvertebrates that consume algae and feed on particles floating through the water column. Macroinvertebrates in lotic reaches were morphologically adapted to cling to rocks in the streamflow, while those in beaver ponds were adapted to living within the fine sediment. Bonneville cutthroat trout collected from lotic reaches were larger than those collected from beaver ponds, while the opposite was true for brown trout collected from lotic reaches. I also found that short-term and long-term diets of both brown trout and Bonneville cutthroat trout were similar between trout caught in beaver pond and lotic reaches. Finally, I found that growth rates of trout were also similar between the two habitats. In conclusion, the structure and function of macroinvertebrates, which are dependent on small-scale habitat features, were more affected by inclusion of beaver ponds to the stream network. Conversely, trout collected from beaver ponds and lotic regions were similar in growth and diet. Considering that beavers are used as a common restoration tool, further studies on the effects of beaver on stream communities is essential.

Users of the Instream Flow Incremental Methodology CTFIM) commonly assume that there is a positive linear relationship between available habitat (WUA) and stream fish biomass. However, several studies have shown a lack cf correlation between WUA and biomass. Such poor relationships may occur if other factors limit fish abundance. Food availability is a potentially important factor limiting abundance of stream fishes and can affect blomass by influencing fish condition (individual weight). I collected rainbow trout (Oncorhynchus mykiss) exposed to different levels of invertebrate-drift density to determine if condition was greater where food was more abundant. I also examined whether size-selective predation and gut fullness varied with drift density. Size-selective predation was not related to drift density. However, condition and gut fullness were both significantly correlated with drift density. Furthermore, changes in drift density appeared to have a stronger influence on small-trout condition than large-trout condition. The results of this study and others support the contention that the reliability of the IFIM might be improved if food availability were incorporated into models.

Spatial heterogeneity of the environment, as measured by floral diversity, composition and structure, is known to influence the distribution and diversity of invertebrates. Heterogeneity brought about by anthropogenic disturbance may be a threat to invertebrate diversity. This thesis investigates the impacts of vegetation heterogeneity at a range of scales on the diversity of invertebrate populations in modified high-altitude indigenous grasslands on the Rock and Pillar Range, Central Otago. Invertebrates were sampled in and on the edges of snow tussock fragments to assess whether species richness increased systematically with fragment area. Invertebrate composition was poorly related to fragment area, plant composition and environmental variables. Taxon richness, abundance and/or diversity for three invertebrate groups increased as fragment area decreased, perhaps reflecting an influx of species from the surrounding matrix. For snow tussock leaf invertebrates in autumn, richness and abundance were at least two times lower in tussocks exposed to the wind than those in the centre of fragments, suggesting selection of habitat may be based on microclimatic characteristics. Invertebrates were sampled from the bases of tussocks after they were clipped to simulate three levels of vertebrate grazing. Invertebrate community composition differed between sites and sampling dates but was unaffected by clipping treatment. At the higher altitude site invertebrate abundance was 1.45 times greater and Shannon-Wiener diversity (H�) 1.22 times lower than at the lower altitude site. The latter sampling date had higher abundance (2.12 times) and taxon richness (1.14 times) than the earlier date. Pitfall-trapped invertebrates in cushionfield, herbfield and snow tussock differed in community composition and often by taxon richness, abundance and diversity. Across habitats, plant composition, plant diversity and some environmental variables were correlated with invertebrate variables, but could not be separated from vegetation type. The invertebrates collected in the course of the study are listed. Four Phyla, eight Classes, 24 orders and over 300 taxa were recorded. Almost all taxa are endemic and many have limited distributions and/or are undescribed. A species list is provided with collection altitude, method and habitat type. Invertebrate assemblages from sites differing in altitude, vegetation type and level of habitat modification on the Rock and Pillar Range are compared. Sites differed in species composition and rank orders of abundance and richness. At lower elevations, invertebrate richness was at least 25% less, and standardised trap abundance at least 44% less, than that at the highest elevation. Richness and abundance of exotic invertebrates decreased with increasing altitude. This thesis highlights several points concerning the study of grassland invertebrates and heterogeneity on the Rock and Pillar Range. First, there are differences in invertebrate assemblages at a range of scales. Conserving invertebrate diversity will therefore require altitudinal sequences and different habitat types, including disturbed areas. At high elevations, tussock habitat may be disproportionately important due to its relative rarity. Second, the effects of disturbance on invertebrates were only visible at large spatial scales. Third, there is a paucity of research on New Zealand invertebrates, especially in regard to terrestrial disturbance, which has resulted in a shortfall of biological, distributional, taxonomic and ecological knowledge.